In the past, blood component preparations have been prepared by removing white blood cells from a blood collected from a donor, and subjecting the blood deprived of the white blood cells to centrifugal separation. For instance, Japanese Patent Laid-open No. 2004-166748 describes a recovery method and a recovery apparatus wherein a blood is made to flow via a blood inlet port into a white blood cell removing filter by use of a blood feeding means so as to catch white blood cells by the white blood cell removing filter, and the blood remaining in the white blood cell removing filter is recovered by a recovery solution, which is a physiological solution.
However, in the recovery method and recovery apparatus described in Patent Document 1, both the blood deprived of the white blood cells and a recovery solution with which the blood remaining in the white blood cell removing filter has been recovered are contained into a recovery bag, and both of them are centrifugally separated, to prepare blood component preparations (CRC, PC and PPP). Therefore, the thus prepared PPP contains the recovery solution (physiological solution) therein, resulting in the problem that the PPP concentration is lowered. In addition, in the CRC and PC thus prepared, the physiological solution is not enough preservative to effect on a lowering in the function of the red blood cells or the platelets. Therefore, there is also the problem that a blood component storage solution (a red blood cell storage solution or a platelet storage solution) has to be newly added.
In view of the foregoing, the present invention has been devised for solving the just-mentioned problems. Accordingly, it is an object of the present invention to provide a blood bag system and a blood treating method wherein a lowering in the concentrations of blood component preparations prepared is obviated, there is no need for a new addition of a blood component storage solution, and it is possible to contrive enhancement of recovery factors of the blood component preparations.